Video data may be compressed by using, for example, an intra-frame compression method or an inter-frame compression method to minimize bandwidth required for transmitting the video data. The inter-frame compression method is generally based on motion estimation. A process of compressing, coding, and decoding an image by using the inter-frame compression method specifically includes the following: An encoder divides a to-be-coded image block into several image sub-blocks of a same size; for each of the image sub-blocks, searches a reference image for an image block that best matches the current image sub-block and uses the image block as a prediction block; subtracts a corresponding pixel value of the prediction block from that of the current image sub-block to obtain a residual; performs entropy coding on a value obtained after the residual is transformed and quantized; and finally sends both a bit stream obtained from the entropy coding and motion vector information to a decoder, where the motion vector information indicates a position difference between the current image sub-block and the prediction block. The decoder of the image first performs entropy decoding on the obtained entropy-coded bit stream, to obtain the corresponding residual and the corresponding motion vector information; obtains a corresponding matched image block (that is, the foregoing prediction block) from the reference image according to the motion vector information; and then obtains a value of each pixel point in the current image sub-block by adding a value of each pixel point in the matched image block and a value of a corresponding pixel point in the residual. For the intra-frame compression method (also referred to as an intra-frame prediction method), a process of compressing, coding, and decoding an image by using the intra-frame compression method specifically includes: dividing an image block into several image sub-blocks, obtaining a reference image block for each of the image sub-blocks according to content of a current frame of image, obtaining a residual of an image sub-block according to the reference image block, performing entropy coding on a value obtained after the residual is transformed and quantized, and writing a result of the coding into a bit stream. A decoder of the image first performs entropy decoding on the obtained entropy-coded bit stream to obtain the corresponding residual and the image sub-blocks into which the image block is divided, obtains the reference image block according to the content of the current frame of image, and obtains a value of each pixel point in a current image sub-block according to a residual between the reference image block and the current image sub-block.
Further, to remove redundancy information from the foregoing image block and improve coding efficiency, in the foregoing coding/decoding technology, the encoder may use, for example, a singular vector decomposition (SVD) technology to perform SVD decomposition on residual data, to obtain an eigenvector matrix (for example, a matrix U and a matrix V), and transform the residual data by using the matrix U and the matrix V to obtain a transform coefficient. However, the decoder cannot perform SVD decomposition on the residual data. Therefore, the encoder needs to transmit, to the decoder, the matrix U and the matrix V that are obtained by performing SVD decomposition on the residual data. Alternatively, several sets of matrices U and V are determined in a coding/decoding system, the encoder transmits an index value corresponding to a matrix U and a matrix V, and the decoder obtains the corresponding matrix U and matrix V by acquiring the index value. In this way, during decoding, the decoder can perform inverse transformation on the transform coefficient by using the matrix U and the matrix V to obtain the residual data, and perform a decoding operation on the residual data.
Therefore, in the existing SVD decomposition technology, the encoder needs to transmit, to the decoder, the matrix U and the matrix V that are obtained by performing SVD decomposition on the residual data, or needs to transmit index values of the several sets of matrices U and V to the decoder. This increases identifier load of a coded bit stream and thereby reduces the coding efficiency.